System Requirements Analysis, 2nd Edition

Figure 3.49 Typical system SBD.

Lower-tier diagrams must expand the interfaces defined on the top-level SBD by creating an expanded SBD for each interface line on the diagram. This process is carried from the top downward progressively in step with the advancing PEBD definition. The product of the interface analysis work should be fed back to help define the expanding architecture responsibility assignments.

Note the use of the lines that are attached at both ends to the same block. These interface lines signify the internal interface for that item. These lines correspond to the diagonal on an n-square diagram. It is useful to illustrate ...